To solve the problem we first need to define the nomenclature by which there is an X amount of water in our body. Let's call this a variable m, corresponding to the total mass in us and whose units are Kilograms.

We understand that one millionth of this mass, a small fraction of it, is the equivalent of that of a Water Molecule.
Assuming this to have the same body of water in our body that amount should be approximately

Density of water molecule



Well it's energy comes from the sun since the sun gives it sunlight to help it grow
The greater the MASS of a moving object, the more kinetic energy it has. <3